The present disclosure relates to detection of overload operation of an electric working machine.
In an electric working machine having a motor as a power source, the motor generates heat in accordance with the magnitude of current flowing at the time of driving the motor and a conduction time to the motor. When this heat generation amount increases, the motor deteriorates.
For this reason, Japanese Patent Application Publication No. 2002-354886 discloses an apparatus that estimates a heat storage amount (in other words, heat generation amount) of a motor from the magnitude of current flowing to the motor and a conduction time to the motor, and, when the estimated heat generation amount exceeds a set value, reduces the current flowing to the motor to protect the motor.